Updating trunk VERSION from 4207.0 to 4208.0

# This is an automated release commit.
# Do not revert without consulting chrome-pmo@google.com.
NOAUTOREVERT=true
TBR=benmason@chromium.org

Change-Id: I9ea83a7a378d8372610527fe171de19838a06f56
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/2306371Reviewed-by: Chrome Release Bot (LUCI) <chrome-official-brancher@chops-service-accounts.iam.gserviceaccount.com>
Cr-Commit-Position: refs/heads/master@{#789774}

chrome/VERSION

 MAJOR=86
 MINOR=0
-BUILD=4207
+BUILD=4208
 PATCH=0